Brain activation during the fist-edge-palm test: a functional MRI study.

The purpose of our study is to clarify, using functional MRI, brain regions activated during the fist-edge-palm task (FEP) compared to relatively simple hand motor tasks using either the right or the left hand in right-handed normal volunteers. The FEP was introduced to detect a disorder of voluntary movement, and it is believed to be closely related to contralateral frontal lobe damage. However, this assumption still remains controversial. Ten subjects participated in this study. Hand motor tasks were as follows: (1) the FEP, in which the subjects were requested to place their hand in three different positions sequentially: a fist resting horizontally, a palm resting vertically, and a palm resting horizontally; (2) a fist-palm task (FP), in which the subjects were asked to clench and unclench their fist alternately; and (3) a control task requiring the subjects to knock lightly with their clenched fist. The contralateral sensomotor and premotor areas were activated in the FP with the right hand and the contralateral sensorimotor, premotor, and supplementary motor areas (SMA) were activated in the FP with the left hand. In the FEP with either hand, bilateral premotor and left parietal areas and ipsilateral cerebellum were also activated as well as contralateral sensorimotor area and SMA. Our results suggest that successful performance of the FEP requires the participation of more brain areas than FP, which may explain why some patients without frontal lobe damage failed to perform the FEP.

Evaluation of pulse sequences used for magnetic resonance sialography.

OBJECTIVES: To determine the most appropriate sequences for the visualization of small parotid ducts in MR sialography. METHODS: MR images of a phantom consisting of distilled water in polyethylene tubes were obtained with turbo-spin echo (TSE), single-shot turbo-spin echo (SSTSE), half-fourier acquisition, single-shot turbo-spin echo (HASTE) and turbo gradient-spin echo (TGSE) pulse sequences and compared visually and quantitatively. MR sialograms obtained from healthy volunteers and patients with Sjögren's syndrome (SS) were obtained using the same four sequences. RESULTS: In the phantom, TSE images were best and the contrast-noise ratio (CNR) highest. In the volunteers, the main ducts were especially clearly visualized with TSE and in SSTSE; however, the majority of secondary and/or tertiary parotid ducts were not depicted by any of the sequences used. In SS patients, images of small main ducts and small pseudocysts were clearer using TSE. However, TSE could not depict the narrow main ducts or peripheral ducts or very small pseudocysts. CONCLUSIONS: TSE is considered the most suitable MR sequence for assessing small parotid gland ducts. However, further improvement is needed since it does not always visualize them sufficiently.

Human cerebellum plays an important role in memory-timed finger movement: an fMRI study.

The purpose of this study was to determine, by using functional magnetic resonance imaging, the areas of the brain activated during a memory-timed finger movement task and compare these with those activated during a visually cued movement task. Because it is likely that subjects engage in subvocalization associated with chronometric counting to achieve accurate timing during memory-timed movements, the authors sought to determine the areas of the brain activated during a silent articulation task in which the subjects were instructed to reproduce the same timing as for the memory-timed movement task without any lip movements or vocalization. The memory-timed finger movement task induced activation of the anterior lobe of the cerebellum (lobules IV and V) bilaterally, the contralateral primary motor area, the supplementary motor area (SMA), the premotor area (PMA), the prefrontal cortex, and the posterior parietal cortex bilaterally, compared with the resting condition. The same areas in the SMA and left prefrontal cortex were activated during the silent articulation task compared with the resting condition. The anterior lobe of the cerebellum on both sides was also activated during the silent articulation task compared with the resting condition, but these activations did not reach statistical significance (P < 0.05 corrected). In addition, the anterior cerebellum on both sides showed significant activation during the memory-timed movement task when compared with the visually cued finger movement task. The visually cued finger movement task specifically activated the ipsilateral PMA and the intraparietal cortex bilaterally. The results indicate that the anterior lobe of the cerebellum of both sides, the SMA, and the left prefrontal cortex were probably involved in the generation of accurate timing, functioning as a clock within the CNS, and that the dorsal visual pathway may be involved in the generation of visually cued movements.

Functional MR imaging of cortical activation of the cerebral hemispheres during motor tasks.

PURPOSE: We used functional MR imaging to evaluate cortical activation in the precentral, central, and postcentral regions of the contralateral and ipsilateral cerebral hemispheres during left- and right-handed motor tasks. METHODS: Ten healthy right-handed volunteers were studied with echo-planner MR imaging (1.5 T) while performing alternating finger apposition tasks with both hands. During the hand tasks, the areas of activated pixels were compared between subregions (precentral, central, and postcentral) of the contralateral and ipsilateral sensorimotor cortex. RESULTS: The activated area of the contralateral sensorimotor cortex was significantly larger than that of the ipsilateral cortex during tasks with either hand, whereas the ipsilateral activated area was significantly larger during the left-handed task than during the right-handed task. Ipsilateral activation was greatest in the precentral region, less in the central region, and least prominent in the postcentral region. CONCLUSIONS: Our results confirmed those of previous investigators that ipsilateral activation is more pronounced during left-sided movements than during right-sided movements. The variation in activation of the precentral, central, and postcentral subregions suggests different roles of the ipsilateral and contralateral hemispheres during motor tasks.

[Cine display of postprocessed 3D MR images of the thoracic aorta].

We have developed a cine display of postprocessed 3D MR images of the thoracic aorta. Maximum intensity projection (MIP) images of the thoracic aorta in each phase were reconstructed from consecutive 2D-cine MR data sets, and displayed in a cine loop. The postprocessed 3D MR images clearly showed the relationship between major cervical branches and aortic pathologies such as aneurysms, and cine display presented the flow pattern in the aorta. 3D-cine MR angiography seems to be useful for follow-up studies of thoracic aortic diseases especially in patients with renal dysfunction.

Evaluation of large intracranial aneurysm with three-dimensional MRI.

OBJECTIVE: The purpose of this study was to evaluate large intracranial aneurysms by contrast-enhanced 3D MRI. MATERIALS AND METHODS: Eleven patients, nine women and two men, were examined. The aneurysms involved the internal carotid artery in seven patients, the middle cerebral artery in one, the basilar artery in two, and the posterior cerebral artery in one. Contrast-enhanced 3D MR images were obtained using FLASH (fast low angle shot) on a 1.5 T system. We obtained axial images first, then sagittal and coronal images by multiplanar reconstruction. Those images were reviewed for comparison with conventional and MR angiography. RESULTS: We could easily evaluate the true aneurysmal size, the intraaneurysmal constitution (patent lumen and intraluminal thrombus), and the detailed relationship of the aneurysm to the surrounding vascular and neural structures. Except for the cavernous internal carotid artery, we could identify the aneurysmal neck by carefully observing axial, sagittal, and coronal images. In addition, the progression of intraaneurysmal thrombosis and the patency of the parent arterial lumen after the endovascular treatment were well appreciated. CONCLUSION: We consider that 3D MRI appears to be useful for evaluation of the large intracranial aneurysm.

T1 measurements with clinical MR units.

To improve accuracy and feasibility of the proton spin-lattice relaxation time (T1) measurements in routine Magnetic Resonance Imaging (MRI), a phantom with polyvinyl alcohol gels and gadrinium diethylene triamine pentaacetic acid solutions was imaged with 1.5T clinical MR units and T1s were calculated by fitting several models to the observed signal intensities. When an inversion-recovery sequence was applied, we were able to measure T1 with a high degree of precision by taking into account the imperfection of the inversion pulse. With a Turbo-fast low angle shot sequence, we were able to obtain T1 in a short time, but low signal-to-noise ratio limited the precision. Signal intensity with SE sequence was susceptible to variation with the effective flip angle of 90 degrees RF pulse and not suited for T1 measurement.

Temporal and geographical clustering of Kawasaki disease in Japan.

Statistical analysis of the data of Nationwide Surveys of Kawasaki Disease in Japan disclosed that (1) the incidence of the disease clustered temporally. The clustering levels were especially high in the years with high incidence rates. (2) Geographical clustering existed in both epidemic year (1982) and non-epidemic years. Incidence rate were lower in rural area than in urban area. These results support the hypothesis that the etiology of Kawasaki Disease is related to some infectious agents.